Liquid-liquid separations of multi-phase solutions often present a multitude of challenges. For example, separating ethanol from a fermentation broth, or separating hydrogen peroxide from an anthraquinone starting solution, present a number of problems including but not limited to: emulsions, long separation times, and large capital and energy expenses. Thus the need for efficient, cost-effective separations is common to the generation of many bio and chemical based products and is a key technical barrier, often accounting for up to about 50% of the overall production costs.
Conventional separation strategies for bio-based products are based on distillation which requires boil-off of both the target bio-based product and large volumes of water, and is therefore very energy intensive. In an effort to reduce costs, the use of membrane based separation systems have been suggested for recovery of ethanol or other alcohols. Most such work has centered on pervaporation, a gas phase dense membrane technique. However, since pervaporation still requires significant heating step, the cost savings are only about 10-15% compared to traditional distillation.
Separation of chemicals such as hydrogen peroxide from starting solutions (i.e. working solution containing dissolved hydrogen peroxide) presents similar separation problems. For example, most known commercial methods for producing hydrogen peroxide use traditional water extraction methods (i.e. use of extraction columns) to separate hydrogen peroxide from an organic working solution. In such systems, the water and organic phases inevitable intermix leading to contamination of the resulting aqueous hydrogen peroxide solution. Cross-contamination between the aqueous and organic phases has been a long standing problem in the production of hydrogen peroxide. This contamination requires extra purification steps which are time and cost intensive. See, PCT Application PCT/SE97/02100, International Publication No. WO 98/28225, which is hereby incorporated by reference in its entirety. A number of similar hydrogen peroxide processes have been developed. See, also U.S. Pat. Nos. 6,596,884; 6,982,072; 5,071,634; and U.S. Patent Application No. US2006/0057057, all of which are hereby incorporated by reference in their entireties. Furthermore, prior art systems do not allow for the simultaneous separation of hydrogen peroxide with oxidation reactions (i.e. of propylene) which could revolutionize the industry.
There exists a need in the art for a new liquid-liquid extraction method for separating target species from starting solutions which overcomes some or all of the problems associated with current methods. There also exists a need in the art of a new system and method that allows simultaneous separation/reactions.